OJ--一元多项式乘法运算和化简

题目：
两输入字符串，多项式，得出多项式乘积的结果。

代码：

/******************************************************************************************************
Description : 对两个输入的一元多项式，进行多项式乘法运算，输出结果一元多项式
Prototype : void PolynomialMultiple (char* InputString1, char* InputString2, char* OutputString)
Input Param : char* InputString1 乘数1多项式字符串
                  char* InputString2 乘数2多项式字符串
Output Param : char* OutputString 乘积多项式字符串
Return Value : void

********************************************************************************************************/
#include <stdio.h>
#include <string.h>
#include <malloc.h>

#define OK 1
#define Error 0

typedef struct Node
{
    int top;
    int front;
    struct Node* next;
}Node;

int InitList(Node **L)
{
    *L=(Node*)malloc(sizeof(Node)); /* 产生头结点,并使L指向此头结点 */
    if(!(*L)) /* 存储分配失败 */
            return Error;
    (*L)->next=NULL; /* 指针域为空 */

    return OK;
}

int insert_list(Node** link_list,int para_top,int para_front)
{
    int j=1;
    Node* p;
    Node* insert_node = NULL;
    Node* pNext;
    p = *link_list;
    pNext = p->next;

    while(pNext != NULL)
    {
        if (pNext->top == para_top)
        {
            pNext->front += para_front;
            return OK;
        }
        else if (pNext->top > para_top)
        {
            p = pNext;
            pNext = p->next;
        }
        else
        {
            insert_node = (Node*)malloc(sizeof(Node));
            insert_node->next = pNext;
            insert_node->top = para_top;
            insert_node->front = para_front;
            p->next = insert_node;
            return OK;
        }
    }

    insert_node = (Node*)malloc(sizeof(Node));
    insert_node->next = pNext;
    insert_node->top = para_top;
    insert_node->front = para_front;
    p->next = insert_node;
    return OK;
}

int insertData(char* InputString,Node** pHeadInput)
{
    if (NULL==InputString || NULL==pHeadInput)
    {
        return OK;
    }
    char* pInput = InputString;
    size_t len = strlen(InputString);
    int para_top,para_front;
    unsigned int i,j,k;
    int flag = 1;
    for(i=0; i<len; i++)
    {
        if (pInput[i]=='X' && pInput[i+1]=='^')
        {
            // 获取指数
            para_top=0,para_front=0;
            for(j=i+2;j<len;j++)
            {
                if (pInput[j]>='0' && pInput[j]<='9')
                {
                    para_top = para_top*10 + pInput[j]-'0';
                }
                else
                {
                    break;
                }
            }
            //获取系数
            k=i-1;
            while (k>=0 && (pInput[k]>='0'&& pInput[k]<='9'))
            {
                k--;
            }
            if (k<0)
            {
                flag = 1;
            }
            else
            {
                if (pInput[k] == '-')
                {
                    flag = -1;
                }
                else
                {
                    flag = 1;
                }

            }
            k++;
            for (;k<i;k++)
            {
                if (pInput[k]>='0' && pInput[j]<='9')
                {
                    para_front = para_front*10 + pInput[k]-'0';
                }
            }

            insert_list(pHeadInput,para_top,para_front*flag);
        }

    }
    return OK;
}

Node* getData(Node* pHeadInput)
{
    if (NULL == pHeadInput)
    {
        return NULL;
    }
    Node* data = (Node*)malloc(sizeof(Node));
    data->front = pHeadInput->front;
    data->top = pHeadInput->top;
    data->next = pHeadInput->next;
    return data;
}

void cpdata2str(char* str, int data)
{
    char* end = str;
    char* begin = str;
    while (data != 0)
    {
        *end = '0' + data%10;
        end++;
        data = data/10;
    }
    end--;
    char tmp;
    while (begin < end)
    {
        tmp = *begin;
        *begin = *end;
        *end = tmp;

        begin++;
        end--;
    }
}

void PolynomialMultiple (char* InputString1, char* InputString2, char* OutputString)
{
    /*在这里实现功能*/
    if (NULL==InputString1 || NULL==InputString2 || NULL == OutputString)
    {
        return;
    }
    Node* pHeadInput1 = NULL;
    Node* pHeadInput2 = NULL;
    Node* pOutput = NULL;
    char* pInput1 = InputString1;
    char* pInput2 = InputString2;
    char* pOutputstr = OutputString;
    InitList(&pHeadInput1);
    InitList(&pHeadInput2);
    InitList(&pOutput);

    insertData(pInput1,&pHeadInput1);
    insertData(pInput2,&pHeadInput2);

    Node* pHead1 = NULL;
    Node* pHead2 = NULL;
    Node* pTmp1 = pHeadInput1;
    Node* pTmp2;
    while ( (pHead1 = getData(pTmp1->next)) != NULL )
    {
        pTmp2 = pHeadInput2;
        while ( (pHead2 = getData(pTmp2->next)) != NULL)
        {
            insert_list(&pOutput,pHead1->top+pHead2->top,pHead1->front*pHead2->front);
            pTmp2 = pHead2;
        }
        pTmp1 = pHead1;
    }

    char str_data[10]={0};
    Node* pHead = NULL;
    int i = 0;
    size_t len=0;
    while ( (pHead = getData(pOutput->next)) != NULL )
    {
        if (pHead->front > 0)
        {
            cpdata2str(str_data, pHead->front);
            len = strlen(str_data);
            if (i!=0)
            {
                *pOutputstr++ = '+';
            }
            strncpy(pOutputstr,str_data,len);
            pOutputstr += len;
            strncpy(pOutputstr,"X^",2);
            pOutputstr += 2;

            memset(str_data,'\0',10);
            cpdata2str(str_data, pHead->top);
            len = strlen(str_data);
            if(len == 0)
            {
                *pOutputstr = '0';
                pOutputstr ++;
            }
            else
            {
                strncpy(pOutputstr,str_data,len);
                pOutputstr += len;
            }
        }
        else if(pHead->front < 0)
        {
            cpdata2str(str_data, -(pHead->front));
            len = strlen(str_data);
            *pOutputstr++ = '-';
            strncpy(pOutputstr,str_data,len);
            pOutputstr += len;
            strncpy(pOutputstr,"X^",2);
            pOutputstr += 2;

            memset(str_data,'\0',10);
            cpdata2str(str_data, pHead->top);
            len = strlen(str_data);
            if(len == 0)
            {
                *pOutputstr = '0';
                pOutputstr ++;
            }
            else
            {
                strncpy(pOutputstr,str_data,len);
                pOutputstr += len;
            }
        }
        pOutput = pHead;
        memset(str_data,'\0',10);
        i++;
    }
    *pOutputstr = '\0';
    return;
}